Method and apparatus for detecting and displaying P-wave and R-wave histograms for an implant medical device

Abstract

A pacemaker, or other implantable medical device, connected to heart tissue, detects atrial and ventricular electrical signals. The pacemaker analyzes the signals to determine whether the signals are representative of P-waves or R-waves according to atrial and ventricular sensitivity threshold values. Signals determined to be P-waves or R-waves are identified as sensed signals. Otherwise the signals are identified as not-sensed signals. The pacemaker further determines whether the sensed signals were detected during a refractory period or an alert period and its current tracking mode (e.g., VDD, DDD vs. DDI, VVI). Information pertaining to these atrial and ventricular signals is transmitted to an external programmer which generates representative histograms. The histograms present the number of counts detected within each of a set of high pass filtered amplitude ranges and further indicate the relative numbers of sensed vs. not-sensed counts. For the sensed counts, the histogram may further indicate the relative numbers of counts detected during refractory periods and alert periods. The histograms additionally show the applicable atrial or ventricular sensitivity threshold values to visually assist a physician in determining whether the threshold values are set properly. An auto-sensitivity adjustment system is also provided to determine optimal sensitivity threshold values.

What is claimed is:  
     
       1. A method for processing information using an implantable medical device and an external display device wherein the implantable medical device is connected to heart tissue and is capable of sensing electrical activity within the heart tissue, the method comprising the steps of: 
       detecting a plurality of signals representative of electrical depolarization activity within the heart tissue connected to the implantable medical device;  
       determining for each respective detected signal whether the signal corresponds to a predetermined type of heart tissue depolarization and the degree of depolarization;  
       transmitting to the external display device a signal representative of the degree of depolarization for each respective detected signal as well as a signal indicative of whether each respective detected signal is of the predetermined type of heart tissue depolarization;  
       receiving the transmitted signals at the external display device;  
       processing the received signals at the external display device to generate a histogram representative of the plurality of detected signals as a function of the degree of depolarization of the signals and further representative of whether the signals were determined to correspond to the predetermined type of heart tissue depolarization; and  
       graphically displaying the histogram at the external display device.  
     
     
       2. The method of claim  1 , wherein the predetermined type of heart tissue depolarization is a P-wave. 
     
     
       3. The method of claim  1 , wherein the predetermined type of heart tissue depolarization is an R-wave. 
     
     
       4. The method of claim  1 , wherein the step of graphically displaying the histogram is performed to identify signals corresponding to the predetermined type of heart tissue depolarization in the histogram as sensed signals and to identify signals not corresponding to the predetermined type of heart tissue depolarization in the histogram as not-sensed signals. 
     
     
       5. The method of claim  4 , further including the step of determining the portion of the sensed signals that were detected during either an alert period or a refractory period. 
     
     
       6. The method of claim  5 , wherein the step of determining the portion of the sensed signals that were detected during either an alert period or a refractory period is determined in conjunction with the current operational mode of the implantable medical device. 
     
     
       7. The method of claim  5 , wherein the step of graphically displaying the histogram includes the step of identifying the respective portions of the sensed signals found to have been detected during the alert period and the refractory period. 
     
     
       8. The method of claim  5 , wherein the step of graphically displaying the histogram additionally includes separately displaying histograms according to the current operational mode of the implantable medical device. 
     
     
       9. The method of claim  1 , wherein at least a portion of the step of determining whether each signal corresponds to a predetermined type of heart tissue depolarization is performed by filtering each signal to determine a filtered amplitude of each signal and by comparing the filtered amplitude of each signal with a predetermined sensitivity threshold value. 
     
     
       10. The method of claim  9 , wherein the step of graphically displaying the histogram includes the step of displaying the predetermined sensitivity threshold value. 
     
     
       11. The method of claim  9 , wherein the step of graphically displaying the histogram includes the step of displaying a range of filtered amplitude values corresponding to predetermined degrees of depolarization. 
     
     
       12. The method of claim  9 , wherein signals that are determined to correspond to the predetermined type of heart tissue depolarization are identified as sensed signals and signals that are determined to not correspond to the predetermined type of heart tissue depolarization are identified as not-sensed signals and wherein the method includes the further step of adjusting the predetermined sensitivity threshold value based upon a comparison of a ratio of the number of sensed and not-sensed signals received. 
     
     
       13. The method of claim  12 , further including the steps of detecting an automode switching event occurring upon the onset of an atrial tachycardia within the heart tissue and wherein the step of adjusting the predetermined sensitivity threshold value is triggered upon detection of the automode switching event. 
     
     
       14. A system for processing information within an implantable medical device and an external display device wherein the implantable medical device is connected to heart tissue and is capable of sensing electrical activity within the heart tissue, the system comprising: 
       means within the implantable medical device for detecting a plurality of signals representative of electrical depolarization activity within the heart tissue connected to the implantable medical device;  
       means for determining the degree of polarization for each respective detected signal and whether the signal corresponds to a predetermined type of heart tissue depolarization; and  
       means within the external display device for processing the signals to graphically display a histogram representative of the plurality of detected signals as a function of the degree of depolarization of the signals and further representative of whether the signals were determined to correspond to the predetermined type of heart tissue depolarization.  
     
     
       15. The system of claim  14 , wherein the predetermined type of heart tissue depolarization is a P-wave. 
     
     
       16. The system of claim  14 , wherein the predetermined type of heart tissue depolarization is an R-wave. 
     
     
       17. The system of claim  14 , wherein the means for processing the signal to graphically display a histogram additionally identifies signals corresponding to the predetermined type of heart tissue depolarization in the histogram as sensed signals and identifies signals not corresponding to the predetermined type of heart tissue depolarization in the histogram as not-sensed signals. 
     
     
       18. The system of claim  17 , further including means for determining the portion of the sensed signals that were detected during either an alert period or a refractory period. 
     
     
       19. The system of claim  18 , wherein the means for determining the portion of the sensed signals that were detected during either an alert period or a refractory period is determined in conjunction with the current operational mode of the implantable medical device. 
     
     
       20. The system of claim  18 , wherein the means for processing the signals to graphically display a histogram additionally operates to identify in the histogram the respective portions of the sensed signals found to have been detected during the alert period or the refractory period. 
     
     
       21. The method of claim  18 , wherein the means for processing the signals to graphically display a histogram additionally includes separately displaying histograms according to the current operational mode of the implantable medical device. 
     
     
       22. The system of claim  14 , wherein the means for determining whether each signal corresponds to a predetermined type of heart tissue depolarization operates, in part, to filter each signal to determine a filtered amplitude of each signal and to compare the filtered amplitude of each signal with a predetermined sensitivity threshold value. 
     
     
       23. The system of claim  22 , wherein the means for processing signals to graphically display the histogram additionally operates to display the predetermined sensitivity threshold value. 
     
     
       24. The system of claim  22 , wherein the means for processing signals to graphically display the histogram additionally operates to display a range of filtered amplitude values corresponding to predetermined degrees of depolarization. 
     
     
       25. The system of claim  22 , wherein the means for determining whether the signal corresponds to a predetermined type of heart tissue depolarization operates to identify signals corresponding to the predetermined type of heart tissue depolarization as sensed signals and to identify signals not corresponding to the predetermined type of heart tissue depolarization as not-sensed signals and wherein the system includes means for adjusting the predetermined sensitivity threshold value based upon a comparison of a ratio of the number of sensed and not-sensed signals received. 
     
     
       26. The system of claim  25 , further including means for detecting an automode switching event occurring upon the onset of an atrial tachycardia within the heart tissue and wherein operation of the means for adjusting the predetermined sensitivity threshold value is triggered upon detection of the automode switching event. 
     
     
       27. A system for processing information within an implantable medical device and an external display device wherein the implantable medical device is connected to heart tissue and is capable of sensing electrical activity within the heart tissue, the system comprising: 
       a detector within the implantable medical device for detecting a plurality of signals representative of electrical depolarization activity within the heart tissue connected to the implantable medical device;  
       a signal type determination unit for determining for each detected signal whether the signal corresponds to a predetermined type of heart tissue depolarization;  
       a histogram generation unit within the external display device for processing the signals to generate a histogram representative of the plurality of signals as a function of the degree of depolarization of the signals and further representative of whether the signals were determined to correspond to the predetermined type of heart tissue depolarization; and  
       a graphic display unit within the external display device for graphically displaying the histogram.  
     
     
       28. The system of claim  27 , wherein the predetermined type of heart tissue depolarization is a P-wave. 
     
     
       29. The system of claim  27 , wherein the predetermined type of heart tissue depolarization is an R-wave. 
     
     
       30. The system of claim  27 , wherein the histogram generation unit identifies signals corresponding to the predetermined type of heart tissue depolarization in the histogram as sensed signals and identifies signals not corresponding to the predetermined type of heart tissue depolarization in the histogram as not-sensed signals. 
     
     
       31. The system of claim  30 , further including a sensed signal classification unit for determining the portion of the sensed signals that were detected during either an alert period or a refractory period. 
     
     
       32. The method of claim  31 , wherein the sensed signal classification unit determines the portion of the sensed signals that were detected during either an alert period or a refractory period in conjunction with the current operational mode of the implantable medical device. 
     
     
       33. The system of claim  31 , wherein the histogram generation unit operates to identify in the histogram the respective portions of the sensed signals found to have been detected during the alert period or the refractory period. 
     
     
       34. The system of claim  31 , wherein the histogram generation unit generates separate histograms to display the sensed signal detected during the alert period or the refractory period according to the current operational mode of the implantable medical device. 
     
     
       35. The system of claim  27 , wherein at least a portion of the signal type determination unit operates to filter each signal to determine a filtered amplitude of each signal and to compare the filtered amplitude of each signal with a predetermined sensitivity threshold value. 
     
     
       36. The system of claim  35 , wherein the graphic display unit is controlled to also display the predetermined sensitivity threshold value. 
     
     
       37. The system of claim  35 , wherein the graphic display unit is also controlled to display a range of filtered amplitude values corresponding to predetermined degrees of depolarization. 
     
     
       38. The system of claim  35 , wherein the signal type determination unit operates to identify signals corresponding to the predetermined type of heart tissue depolarization as sensed signals and to identify signals not corresponding to the predetermined type of heart tissue depolarization as not-sensed signals and wherein the system includes a sensitivity adjustment unit for adjusting the predetermined sensitivity threshold value based upon a comparison of a ratio of the number of sensed and not-sensed signals identified. 
     
     
       39. The system of claim  38 , further including an automode switching event detection unit for detecting an automode switching event occurring upon the onset of an atrial tachycardia within the heart tissue and wherein operation of the sensitivity adjustment unit is triggered upon detection of an automode switching event. 
     
     
       40. A system for processing information within an implantable medical device wherein the implantable medical device is connected to heart tissue and is capable of sensing electrical activity within the heart tissue, the system comprising: 
       a detector within the implantable medical device for detecting a plurality of signals representative of electrical depolarization activity within the heart tissue connected to the implantable medical device;  
       a signal type determination unit for determining for each detected signal whether the signal corresponds to a predetermined type of heart tissue depolarization;  
       a histogram generation unit for processing the signals to generate histogram data representative of the plurality of signals as a function of the degree of depolarization of the signals and further representative of whether the signals were determined to correspond to the predetermined type of heart tissue depolarization; and  
       a sensitivity adjustment unit for determining a sensitivity threshold level for determining the type of heart tissue depolarization in response to the generated histogram data.  
     
     
       41. The system of claim  40 , wherein the predetermined type of heart tissue depolarization is a P-wave. 
     
     
       42. The system of claim  40 , wherein the predetermined type of heart tissue depolarization is an R-wave. 
     
     
       43. The system of claim  40 , wherein the histogram generation unit identifies signals corresponding to the predetermined type of heart tissue depolarization in the histogram as sensed signals and identifies signals not corresponding to the predetermined type of heart tissue depolarization in the histogram as not-sensed signals. 
     
     
       44. The system of claim  43 , further including a sensed signal classification unit for determining the portion of the sensed signals that were detected during either an alert period or a refractory period. 
     
     
       45. The system of claim  44 , wherein the sensed signal classification unit additional determines the portion of the sensed signal detected during either an alert period or a refractory period in conjunction with the current operational mode of the implantable medical device. 
     
     
       46. The system of claim  44 , wherein the histogram generation unit operates to identify in the histogram data the respective portions of the sensed signals found to have been detected during the alert period or the refractory period. 
     
     
       47. The system of claim  44 , wherein the histogram generation unit separately displays histograms according the current operational mode of the implantable medical device to identify in the histogram data the respective portions of the sensed signals found to have been detected during the alert period or the refractory period. 
     
     
       48. The system of claim  40 , wherein at least a portion of the signal type determination unit operates to filter each signal to determine a filtered amplitude of each signal and to compare the filtered amplitude of each detected signal with a determined sensitivity threshold value. 
     
     
       49. The system of claim  48 , wherein the signal type determination unit operates to identify signals corresponding to the predetermined type of heart tissue depolarization as sensed signals and to identify signals not corresponding to the predetermined type of heart tissue depolarization as not-sensed signals and wherein the sensitivity adjustment unit adjusts the determined sensitivity threshold value based upon a comparison of a ratio of the number of sensed and not-sensed signals identified. 
     
     
       50. The system of claim  40 , further including an automode switching event detection unit for detecting an automode switching event occurring upon the onset of an atrial tachycardia within the heart tissue and wherein operation of the sensitivity adjustment unit is triggered upon detection of an automode switching event.